In the light of a recent study entitled “Measuring Underwater Noise Levels Radiated by Ships in Indian Waters”, there is growing concern about underwater noise emissions (UNE) from ships in Indian waters and the threat they pose to the marine ecosystem. The measurement of ambient noise levels was conducted using a hydrophone autonomous system, approximately 30 nautical miles from the Goa coastline.
Key Findings of the Study
The sound pressure levels of UNE in Indian waters range between 102-115 decibels, relative to one microPascal (dB re 1µ Pa), with scientists utilizing 1µPa as the benchmark for underwater sound. Interestingly, the East Coast level appears marginally higher than that of the West. Furthermore, there has been a substantial increase of about 20 dB re 1µPa.
Continual shipping movement is identified as a principal factor in the escalation of global ocean noise level. These UNE are proving detrimental to marine mammals such as Bottlenose Dolphins, Manatees, Pilot Whales, Seals, and Sperm Whales, as sound forms the main energy for numerous behavioural activities of these animals, including mating, communal interaction, feeding, and foraging.
The Consequences of UNE
The frequencies of ships’ underwater self-noise and machinery vibration levels are obscuring marine species’ communication frequencies in the low-frequency domain of less than 500 Hz. This phenomenon, known as masking, can result in a shift of migration routes for marine species to shallow regions, making it challenging for them to return to deeper waters. Meanwhile, sound radiations from ships over a prolonged period can lead to internal injuries, hearing loss, changes in behaviour, and added stress among marine creatures.
Understanding Marine Sound Pollution
Marine sound pollution pertains to excessive or harmful noise introduced to the oceanic environment. It originates from various human activities, including shipping, military sonar, oil and gas exploration, and recreational pursuits like boating and jet-skiing. This type of pollution can interfere with communication, navigation, and hunting behaviours of marine mammals such as whales, dolphins, and porpoises, and may cause physiological harm or death.
Efforts To Protect Marine Ecosystems
At the global level, several initiatives are in place to safeguard marine habitats. These include the Global Programme of Action (GPA) for the Protection of the Marine Environment from Land-based Activities, MARPOL Convention (1973), and The London Convention (1972).
India also has measures in place to protect its marine life. The Wild Life Protection Act of India (1972) provides statutory protection to many marine animals while the Coastal Regulation Zone (CRZ) prohibits developmental activities and waste disposal in delicate coastal ecosystems. Furthermore, the Centre for Marine Living Resources and Ecology (CMLRE) is tasked with developing management strategies for marine living resources through ecosystem monitoring and modeling activities.
